Circuit breaker



y 26, 1955 L. c. WHITMAN ETAL 2,714,143

CIRCUIT BREAKER Filed May 6, 1954 2 Sheets-Sheet l Law/eves C. Wfi/fman,r I. I l I V 1 James 1?. Barr,

J y 1955 L. c. WHITMAN ET AL CIRCUIT BREAKER 2 Sheets-Sheet 2 Filed May6, 1954 [Era/ ora Lawrence C. YEW/7727417,

James; Ba M me/fflfl'orl gq Mwm 2,714,1 2.? Patented July 26, 1955cracmr BREAKER Lawrence Q. Whitman, Pittsfield, Mass., and James R.

Barr, Rome, Ga., assignors to General Electric Company, a corporation ofNew York Application May 6, 1954, Serial No. 427,904 @laims. (Cl.200-140) This invention relates to a circuit breaker or protectiveswitch, and more particularly, to a circuit breaker or protective switchfor interrupting the electrical circuit of an electrical apparatus uponoverheating of same, said circuit breaker or protective switch beingautomatically operative to reclose said circuit upon cooling of saidapparatus.

Available on the commercial market are a plurality of circuit breakersor protective switches designed to interrupt the electrical circuit ofan electrical apparatus upon overheating of same or the like. Some ofsaid devices after interrupting said electrical circuit do notautomatically reclose said electrical circuit upon cooling of saidoverheated electrical apparatus, but must be closed manually.Accordingly, an interruption in an electrical circuit will result untilsuch time as an operator can manually reclose the circuit breaker orprotective switch.

it is an object of this invention to provide a circuit breaker orprotective switch for automatically interrupting the electrical circuitof an electrical apparatus upon overheating of same or the like, saidcircuit breaker or protective switch being automatically operative toreclose said circuit upon cooling of said apparatus.

Our invention comprises an electrical protective switch having a pair ofcontacts adapted to be positioned in an electrical circuit, one of saidcontacts being stationary and the other of said contacts being movable,a spring toggle mechanism for snapping said movable contact intoengagement and disengagement with said stationary contact, a closedhollow cylindrical bellows actuator for actuating said spring togglemechanism, one end of said bellows actuator being stationary and theother end of said bellows actuator being movable, a spring interiorly ofsaid bellows actuator connected to opposite ends thereof andcontinuously biasing said movable end for movement in one direction withrespect to said stationary end, and a vaporizable fluid having highpressure vapors formed therefrom at a predetermined temperaturecooperative with said bellows actuator whereby said high pressure vaporsare operative to move said movable end in a direction opposite to saidone direction.

Our invention further comprises an electrical protective switch forprotecting an electrical apparatus from overheating by interruption ofthe electrical circuit thereof and for automatically closing saidcircuit after cooling of said apparatus, said apparatus enclosed withina casing and said switch disposed within said casing, said switchcomprising a pair of contacts positioned in said circuit, one of saidcontacts being movable and the other of said contacts being fixed, aspring toggle mechanism for snapping said movable contact intoengagement and disengagement with said fixed contact, a closed hollowcylindrical bellows actuator for actuating said spring toggle mechanism,one end of said bellows actuator being fixed and the other end of saidbellows actuator being movable, a spring interiorly of said bellowsactuator connected to opposite ends thereof and continuously biasingsaid movable end for movement in one direction with respect to saidfixed end, and a vaporizable liquid having high pressure vapors formedtherefrom at a predetermined temperature cooperative with said bellowsactuator whereby said movable end is moved in a direction opposite tosaid one direction.

The features of our invention which we believe to be novel are set forthwith particularity in the appended claims. Our invention itself,however, both as to its organization and method of operation, togetherwith further objects and advantages thereof may best be understood byreference to the following description taken in connection with theaccompanying drawings.

In the drawings, Fig. 1 is an elevational side view of one form of ourinvention. Fig. 2 is an enlarged detailed elevational side view of thecircuit breaker or protective switch shown in Fig. 1 when in the closedposition. Fig. 3 is a front view of the circuit breaker or protectiveswitch shown in Fig. 2. Fig. 4 is a side view identical to that of Fig.2 when the circuit breaker or protective switch is in the open position.Fig. 5 is an elevational side view of another form of our invention.Fig. 6 is a diagrammatic electrical circuit illustration of both formsof our invention. Throughout the various figures, like referencenumerals will be used to indicate identical parts.

Referring now to the drawings, and more particularly to Fig. 1, showntherein is an electrical apparatus 5, as a stationary electricalinduction apparatus or transformer, positioned within a casing or tank6. Casing or tank 6 is partially filled with a vaporizable dielectriccooling liquid '7, and the electrical apparatus 5 is immersed in coolingliquid 7. Defined by the casing or tank 6 above the surface level of thecooling liquid 7 is a vaporization and condensation chamber or space Thevaporizable dielectric cooling liquid 7 has a predetermined boilingpoint temperature within the normal operating temperature range of theelectrical apparatus 5. During normal operation of the electricalapparatus 5, vapors are formed from the cooling liquid 7 in thevaporization and condensation chamber or space 8 and condensed thereinthus cooling the electrical apparatus 5. When the electrical apparatus 5becomes overheated, said vapors will accumulate in the vaporization andcondensation chamber or space 8 at very high pressures. Mounted on aportion of the casing or tank 6 is a circuit breaker or protectiveswitch 9 disposed within the chamber or space 3. The circuit breaker orprotective switch 9 is operative to interrupt the electrical circuit ofthe electrical apparatus 5 in response to said very high pressurevapors, and then to automatically reclose said electrical circuit afterthe electrical apparatus 5 has cooled.

Referring now more particularly to Figs. 2 and 3, the circuit breaker orprotective switch 9 comprises an inverted L-shaped bracket or support12. Connected to the downwardly extending leg portion of bracket 12 anddisposed between the two leg portions of the bracket 12 is an electricalinsulating material base 13. Carried by the base 13 are two pairs ofengageable and disengageable contacts and a spring toggle mechanism. Onecontact 14 of each pair of engageable and disengageable pair of contactsis fixed or stationary, and another contact 15 of each pair ofengageable and disengageable contacts is movable, and said spring togglemechanism is adapted to snap the movable contacts 15 open or close withrespect to the fixed or stationary contacts 14 upon actuation of saidspring toggle mechanism.

integrally formed in the base 13 are two spaced and parallel wallportions 17. Each of the wall portions 17 has an acute V-shaped groove18 formed therein, and the V-shaped grooves 18 are adapted to serve asthe pivot points for a U-shaped member 19. Each of the leg portions ofthe U-shaped member 19 are bent at an obtuse angle, and the extremitiesof said leg portions have acute V-shaped pointed ends. Said pointed endsare disposed in the acute V-shaped grooves 18 whereby the U-shapedmember 19 can be rocked or pivoted downwardly and upwardly within thegrooves 18.

Disposed midway between the wall portions 17 and the spaced leg portionsof U-shaped member 19 is a flat U-shaped member 21.lJ-shap'ed'm'e'mberll is stationary or fixed by two pins 22 and 23passing through the wall portions 17 and the extremities of the spacedleg portions of U-shaped' member 21. U-shaped member 21 has two stoptabs 24 and 25 formed thereon cooperative with a pair of tabs 26 formedon the U-shaped member 19. The base or leg connecting portion ofU-shaped member 19 is superposed with respect to the base or legconnecting portion of flat U-shaped member-'21. The

pair of tabs 26' are spaced from each other and disposed along oppositesides of the flat U-shaped member 21 between the stop tabs 24 and 25.Downward movement of the U-shaped member 19 will be stopped when thetabs 26 strike the stop tab 25, see Fig. 2, and upward movement of theU-shaped member 19 will be stopped when the tabs 26 engage the stop tab24, see Fig. 4.

A pair of switch arms 28 are disposed between the wall portions 17 andthe flat U-shaped member 21 and are pivoted at their upper ends to thepin 22. The lower ends of the switch arms 28 are joined by an integralT-portion 2.9 which carries the movable contacts 15. A lever 39 disposedbetween the switch arms 28 is connected to the switch arms 23 by a pin31 passing through the switch arms 28 and the lever 30. Another pin 32connects an opposite end of the lever 31} to a pair of levers 331 Thepin 32 is disposed generally between the spaced leg portions of the fiatU-shaped member 21 and the levers 33 extend along opposite sides of thefiat U-shaped member 21 and are connected thereto by a pin 34. Extendingfrom opposite ends or the pin 32 to the tabs 26 are a pair of springs35. As will be obvious to those skilled in the art, when the U-shapedmember 19 is pivoted or rocked upwardly, see Fig. 4, the contacts 14 and15 will be snapped open; and when the U-shaped member 19 is pivoted orrocked downwardly, see Fig. 2, the contacts 14 and 15 will be snappedclosed.

The means for actuating the spring toggle mechanism for snappingengagement and disengagement of the contacts 14 and 15 comprises aclosed hollow cylindrical bellows-like actuator. Said bellows-likeactuator comprises two telescopic cylindrical members 37 and 38. Thetelescopic members 37 and 38 are hermetically sealed within anaccordion-like sleeve 39, and the interior of the telescopic members 37and 38 and the sleeve 39 may have a vacuum or predetermined gas pressureformed therein. Concentrically disposed about the telescopic members 37and 38 is a compressed spring 40. Spring 40 is disposed between thetelescopic members 37 and 38 and the accordion-like sleeve 39, and isconnected at its opposite ends to opposite end portions of the closedhollow cylindrical bellows actuator. The upper end of the closed hollowcylindrical bellows actuator is stationary or fixed and the lower end ofthe bellows actuator is movable with respect to said fixed end andconnected to the U-shaped member 19 by a pair of levers 41.

Referring now to Fig. 6, the two pairs of engageable and disengageablecontacts 14 and are adapted to be disposed in the two secondary lineleads 43 of the secondary electrical windings 42 of the stationaryelectrical apparatus or transformer 5, the neutral midpoint of saidsecondary electrical windings 42 being grounded. As will be obvious tothose skilled in the art, the dielectric cooling liquid 7' has apredetermined boiling point temperaturewhereby when the maximum safeoperating temperature limit of the electrical apparatus 5 has beenexceeded the vapor pressure in the chamber or space 8 will have attaineda high enough pressure to collapse the'bellows actuator. When thebellows actuator is collapsed the lower movable end thereof movesupwardly and simultaneously moves'the U-shaped member 19counterclockwise to snap the contacts 14 and 15 open, see Fig. 4. Whenthe electrical circuit of the electrical apparatus 5 is interrupted, theelectrical apparatus 5 has an opportunity to cool to a temperature belowsaid maximum safe operating temperature limit. As the vapors within thechamber or space 8 condense, the pressure within said chamber or space 3decreases. After the electrical apparatus 5 has cooled and the vaporpressure within chamber or space 8 has decreased, the compressed springwill expand the bellows actuator. As the bellows actuator expands, thelower end thereof moves downwardly and simultaneously rocks the U-shapedmember 19 clockwise to snap the contacts 14 and 15 closed to restoreelectrical service, see Fig. 2. In some cases, it may be desirable toposition the contacts 14 and 15 in the dielectric liquid 7 to providebetter arc quenching. However, in all cases the bellows actuator shouldbe in the gas space 8. By a proper selection and correlation of thecompressed spring 40, the pressure interiorly of the bellows actuator,and the vapor pressure within the chamber of space 8, the tripping openand reclosing temperature limits of the circuit breaker 9 as well as thespan between said limits can be accurately determined and varied to meetindividual requirements. The form of invention disclosed in Fig. 1 is ofparticular value in vaporization cooled electrical installations whereprotection from excessive pressures on overload is a vital safetyrequirement. The arrangement shown in Fig. 1 might not operate reliablyin conventional electrical apparatus installations not dependent uponvaporization and condensation cooling because of the lack of avaporizable liquid to rapidly create pressure in the casing in responseto the hottest part of the apparatus.

Referring now to Fig. 5, shown therein is another form of our inventionnot dependent upon vaporiaztion and condensation cooling of theelectrical apparatus 5. In this form of invention the bellows actuatorexpands to trip the circuit breaker or protective switch open, and

'contracts to reclose the circuit breaker or protective witch.Accordingly, the bellows actuator in this form of invention is disposedbelow the circuit breaker or protective switch spring toggle mechanismand contacts 14 and 15. The lower end of the bellows actuator is fixedor stationary, the upper end of the bellows actuator is movable, and thecompressed spring 40 of the first form of invention is replaced by atension spring 45 which continuously tends to collapse the bellowsactuator. A thermal bulb 46 having a vaporizable liquid therein isdisposed within or adjacent to the electrical apparatus 5 to beprotected. The thermal bulb 46 is connected by a conduit 47 to theinterior of the bellows actuator, and otherwise the form of theinvention disclosed in Fig. 5 is identical in construction to the formof invention heretofore described. When the electrical apparatus to beprotected from overheating or the like exceeds a predetermined safeoperating temperature limit for said electrical apparatus, thevaporizable liquid within the thermal bulb 46 will have vaporized intothe interior of the bellows actuator to expand same against thecontracting action of tension spring 45. As the upper movable end of thebellows actuator moves upwardly, the U-shaped member 19 will be rockedcounterclockwise to snap the contacts 14 and 15 open. With the circuitof the electrical apparatus to be protected interrupted, the electricalapparatus will cool from its overheated or overloaded condition. Aftersufficient cooling, the vapors within the bellows actuator will havecondensed sufficiently to permit the tension spring 45 to contract thebellows actuator and simultaneously pivot the U-shaped member 19clockwise to automatically reclose the contacts 14 and 15 and restoreelectrical service.

While there have been shown and described particular embodiments of theinvention, it will be obvious to those skilled in'the art that changesand modifications may be made without departing from the invention, andthat it is intended by the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. In an electrical apparatus enclosed in a casing, said apparatussubmerged in a dielectric cooling liquid having a boiling pointtemperature within the normal operating temperature range of saidapparatus, a circuit breaker positioned in said casing above the surfacelevel of said liquid, said circuit breaker comprising a pair ofengageable and disengageable contacts in the electrical circuit of saidapparatus and an expansible and collapsible bellows actuator forengaging and disengaging said contacts, said bellows actuatorcollapsible and operable to disengage said contacts in response to apredetermined pressure increase in said casing, and said bellowsexpansible and operable to engage said contacts in response to apredetermined pressure decrease in said casing 2. In an electricalapparatus submerged in a dielectric cooling liquid Within a closedcasing, said liquid partially filling said casing, said liquid having apredetermined boiling point temperature whereby high pressure vapors ofsaid liquid are formed in said casing when a predetermined maximumoperating temperature of said apparatus is exceeded, a pair of contactsin the electrical circuit of said apparatus and means for automaticallyopening said contacts when said maximum operating temperature isexceeded and for automatically closing said contacts subsequent to saidopening subsequent to a predetermined decrease in the temperature ofsaid apparatus below said maximum operating temperature comprising abellows actuator disposed in said high pressure vapors, said bellowsactuator collapsible and operable in response to said high pressurevapors to open said contacts and expansible and operable in response tosaid predetermined decrease to close said contacts.

3. In a stationary electrical induction apparatus immersed in adielectric cooling liquid within a closed casing partially filled withsaid liquid, a vaporization and condensation chamber in said casingabove the surface level of said liquid, said liquid having apredetermined boiling point temperature whereby high pressure vapors ofsaid liquid are formed in said chamber when the temperature of saidapparatus exceeds a predetermined maximum operating temperature, a pairof contacts in the electrical circuit of said apparatus, a spring togglemechanism for rapidly snapping said contacts open and close, and aclosed bellows actuator for actuating said spring toggle mechanism, saidclosed bellows actuator disposed in said chamber, said closed bellowsactuator having a compressed spring therein, said bellows actuatorcollapsible and expansible respectively in response to said highpressure vapors and a predetermined decrease in the pressure thereof.

iii)

4. In a transformer immersed in a dielectric cooling liquid within aclosed tank partially filled withsaid liquid, a vaporization andcondensation chamber defined by said tank above the surface level ofsaid liquid, said liquid having a boiling point temperature within thenormal operating temperature range of said transformer whereby vapors ofsaid liquid are formed in said chamber during operation of saidtransformer, a closed bellows actuator disposed in said chamber, acompressed spring in said bellows actuator bearing against opposite endsthereof and tending to expand said bellows actuator, said vapors tendingto collapse said bellows actuator, a pair of contacts disposed in a linelead of said transformer, and a spring toggle mechanism connecting saidbellows actuator to one of said contacts whereby said contacts areautomatically snapped closed when said bellows actuator is collapsed andautomatically opened when said bellows actuator is expanded.

5. In a transformer immersed in a dielectric cooling liquid within atank partially filled with said liquid, said tank defining avaporization and condensation chamber above the surface level of saidliquid, said liquid having a predetermined boiling point temperaturewithin the normal operating temperature range of said transformerwhereby vapors of said liquid are formed in said chamber during normaloperation of said transformer, a device for prohibiting overheating ofsaid transformer, said device operable to interrupt the circuit of saidtransformer upon overheating thereof and operable to automaticallyreclose said circuit upon cooling of said transformer subsequent to saidoverheating, said device comprising a pair of contacts disposed in saidliquid in one line lead of said transformer and a closed hollowcylindrical bellows actuator disposed in said chamber, said bellowsactuator having a compressed spring therein bearing against oppositeends thereof and continuously tending to expand said bellows actuator,said vapors continuously tending to compress said bellows actuator, oneof said contacts being movable, said bellows actuator being fixed at oneend thereof and movable at another end thereof, said another endconnected by a spring toggle mechanism to said movable contact wherebysaid contacts are automatically snapped open and close respectively inresponse to a predetermined compression and expansion of said bellowsactuator.

References Cited in the file of this patent UNFED STATES PATENTS2,096,709 Dunn Oct. 26, 1937 2,341,241 Reynolds Feb. 8, 1944 2,459,522Grooms Fan. 18, 1949 2,504,435 Matteson Apr. 18, 1950

